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Browsing by Author "Lee, Seung-Young"
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Item Cholesteryl Ester Accumulation Induced by PTEN Loss and PI3K/AKT Activation Underlies Human Prostate Cancer Aggressiveness(Elsevier, 2014-03-04) Yue, Shuhua; Li, Junjie; Lee, Seung-Young; Lee, Hyeon Jeong; Shao, Tian; Song, Bing; Cheng, Liang; Masterson, Timothy A.; Liu, Xiaoqi; Ratliff, Timothy L.; Cheng, Ji-Xin; Department of Pathology & Laboratory Medicine, IU School of MedicineAltered lipid metabolism is increasingly recognized as a signature of cancer cells. Enabled by label-free Raman spectromicroscopy, we performed quantitative analysis of lipogenesis at single cell level in human patient cancerous tissues. Our imaging data revealed an unexpected, aberrant accumulation of esterified cholesterol in lipid droplets of high-grade prostate cancer and metastases. Biochemical study showed that such cholesteryl ester accumulation was a consequence of loss of tumor suppressor PTEN and subsequent activation of PI3K/AKT pathway in prostate cancer cells. Furthermore, we found that such accumulation arose from significantly enhanced uptake of exogenous lipoproteins and required cholesterol esterification. Depletion of cholesteryl ester storage significantly reduced cancer proliferation, impaired cancer invasion capability, and suppressed tumor growth in mouse xenograft models with negligible toxicity. These findings open opportunities for diagnosing and treating prostate cancer by targeting the altered cholesterol metabolism.Item Neuroprotective Ferulic Acid (FA)-Glycol Chitosan (GC) Nanoparticles for Functional Restoration of Traumatically Injured Spinal Cord(Elsevier B.V., 2014-02) Wu, Wei; Lee, Seung-Young; Wu, Xiangbing; Tyler, Jacqueline Y.; Wang, He; Ouyang, Zheng; Park, Kinam; Xu, Xiao-Ming; Cheng, Ji-Xin; Department of Neurological Surgery, IU School of MedicineAn urgent unmet need exists for early-stage treatment of spinal cord injury (SCI). Currently methylprednisolone is the only therapeutic agent used in clinics, for which the efficacy is controversial and the side effect is well-known. We demonstrated functional restoration of injured spinal cord by self-assembled nanoparticles composed of ferulic acid modified glycol chitosan (FA-GC). Chitosan and ferulic acid are strong neuroprotective agents but their systemic delivery is difficult. Our data has shown a prolonged circulation time of the FA-GC nanoparticles allowing for effective delivery of both chitosan and ferulic acid to the injured site. Furthermore, the nanoparticles were found both in the gray matter and white matter. The in vitro tests demonstrated that nanoparticles protected primary neurons from glutamate-induced excitotoxicity. Using a spinal cord contusion injury model, significant recovery in locomotor function was observed in rats that were intravenously administered nanoparticles at 2 h post injury, as compared to non-improvement by methylprednisolone administration. Histological analysis revealed that FA-GC treatment significantly preserved axons and myelin and also reduced cavity volume, astrogliosis, and inflammatory response at the lesion site. No obvious adverse effects of nanoparticles to other organs were found. The restorative effect of FA-GC presents a promising potential for treating human SCIs.Item PEG-PDLLA micelle treatment improves axonal function of the corpus callosum following traumatic brain injury(Mary Ann Liebert, Inc., 2014-07-01) Ping, Xingjie; Jiang, Kewen; Lee, Seung-Young; Cheng, Ji-Xing; Jin, Xiaoming; Department of Anatomy & Cell Biology, IU School of MedicineThe initial pathological changes of diffuse axonal injury following traumatic brain injury (TBI) include membrane disruption and loss of ionic homeostasis, which further lead to dysfunction of axonal conduction and axon disconnection. Resealing the axolemma is therefore a potential therapeutic strategy for the early treatment of TBI. Monomethoxy poly (ethylene glycol)-poly (D, L-lactic acid) di-block copolymer micelles (mPEG-PDLLA) have been shown to restore depressed compound action potentials (CAPs) of spinal axons and promote functional recovery after spinal cord injury. Here, we evaluate the effect of the micelles on repairing the injured cortical axons following TBI. Adult mice subjected to controlled cortical impact (CCI) were treated with intravenous injection of the micelles at 0 h or 4 h after injury. Evoked CAPs were recorded from the corpus callosum of coronal cortical slices at 2 days after injury. The CCI caused significant decreases in the amplitudes of two CAP peaks that were respectively generated by the faster myelinated axons and slower unmyelinated axons. Micelle treatment at both 0 h and 4 h after CCI resulted in significant increases in both CAP peak amplitudes. Injection of fluorescent dye-labeled micelles revealed high fluorescent staining in cortical gray and white matters underneath the impact site. Labeling membrane-perforated neurons by injecting a membrane impermeable dye Texas Red-labeled dextran into lateral ventricles at 2 h post-CCI revealed that immediate micelle injection after CCI did not reduce the number of dye-stained cortical neurons and dentate granule cells of the hippocampus, indicating its ineffectiveness in repairing plasma membrane of neuronal somata. We conclude that intravenous administration of mPEG-PDLLA micelles immediately or at 4 h after TBI allows brain penetration via the compromised blood brain-barrier, and thereby improves the function of both myelinated and unmyelinated axons of the corpus callosum.